Papermaking fabric

ABSTRACT

A multi-ply woven fabric especially for use as a Fourdrinier forming belt and so constructed that it has a relatively long useful life. The surface area of the fabric is at least about nine percent open, and the fabric includes at least two woven plies with the top or face ply having a considerably greater number of yarns per square inch thereof than the bottom or backing ply, and wherein the yarns in the bottom ply are substantially larger than and have a substantially greater aggregate cross-sectional area than the yarns in the top ply.

United States Patent [1 1 Slaughter 1 PAPERMAKING FABRIC [75] Inventor:Philip H. Slaughter, Charlotte, NC.

[73] Assignees: Evans S. Creech; Jimmie O.

I-Iulchins; John W. Whitley, all of Charlotte, NC. part interest to each[22] Filed: Nov. 21, 1973 [21] Appl. No.: 417,872

[52] US. Cl. 139/425 A; l62/D1G. l [51] Int. Cl. D03d 15/00; D03d 15/02;D2lf1/1O [58] Field of Search 139/425 A, 425 R, 420 R, 139/383 A,408-415; 162/348, 349, DIG. l;

[56] References Cited UNITED STATES PATENTS 1,879,243 9/1932 Hoffacker139/415 2,157,082 5/1939 Milnes 130/383 A 2,742,059 4/1956 Watts 139/4092,934,097 4/1960 Hindle et a1. 139/383 A 2,936,796 5/1960 Hindle eta1. 1. 139/383 A 2,949,134 8/1960 Hindle et a1. 139/383 A 3,127,3083/1964 Justus et al. 139/425 A [451 May 27, 1975 3,222,246 12/1965 Lee162/349 3,322,617 5/1967 Osborne 162/349 X 3,325,909 6/1967 Clark 1.74/239 FOREIGN PATENTS OR APPLICATIONS 22,813 3/1962 Germany 162/D1G1 147-44,444 11/1972 Japan 4 .1 162/D1G. 1 297,739 4/1971 U.S.S,R l62/DIG.1

Primary Examinerlames Kee Chi Attorney, Agent, or Firm-Parrott, Bell,Seltzer, Park & Gibson [57] ABSTRACT A multi-ply woven fabric especiallyfor use as a Fourdrinier forming belt and so constructed that it has arelatively long useful life. The surface area of the fabric is at leastabout nine percent open, and the fabric includes at least two wovenplies with the top or face ply having a considerably greater number ofyarns per square inch thereof than the bottom or backing ply, andwherein the yarns in the bottom ply are substantially larger than andhave a substantially greater aggregate cross-sectional area than theyarns in the top 13 Claims, 6 Drawing Figures PAPERMAKING FABRIC Thisapplication is an improvement of my copending application Ser. No.4l7,873, filed concurrently herewith and entitled WOVEN FOURDRINIERFABRIC.

This invention relates to an improved multi-ply woven fabric especiallyfor use in the construction of endless belts, commonly known asFourdrinier forming belts, employed in the manufacture of paper andcomparable fibrous materials.

It is well known in the papermaking industry that paper is produced byflowing a slurry of pulp or cellulosic fibers and/or other papercomponents mixed with water and/or other liquid onto a moving endlessbeit commonly known as a Fourdrinier forming belt. Fourdrinier formingbelts are necessarily of substantial length and are porous so that amajor portion of the liq uid is removed from the slurry by drainage.After most of the liquid has been removed, the thus formed paper web istransferred to a so-called paperrnakers drier felt which conveys thepaper web through the nips of heated cylinders to extract the residualmoisture from the paper web.

Papermakers drier felts are generally formed of a very coarse, compactlywoven fabric. Fourdrinier forming belts, on the other hand, are quitedistinct from drier felts in that at least the fact thereof must be of afine mesh weave of relatively small strands or yarns with the meshthereof being of such size and count as to provide at least about ninepercent open area in the belt to permit ready drainage therethrough ofliquid from a slurry while providing a satisfactory supporting surfacefor obtaining the desired quality paper product. Fourdrinier formingbelts may be woven from metallic, natural and/or synthetic warp and weftyarns or strands, and it is necessary that such belts are of hightensile strength so as to be placed under substantial tension, and theyalso must be highly stable both widthwise and lengthwise of the belt. Inother words, it is highly desirable that the belt is so constructed thatit will be subject to very little, if any, stretch or elongation andlorcontraction in normal use and so that the strands or yarns thereof willnot shift excessively relative to each other. However, Fourdrinierforming belts have been so constructed heretofore as to have anundesirable relatively short useful life because of the flexing,relatively rapid abrasion and consequent fracture of the surfaces ofthose portions of the strands of the belt which engage and necessarilycreep on the supporting rolls and other supporting surfaces of apapermaking machine. Such portions of the strands in the Fourdrinierforming belt are generally known as warp knuckles" and/or shuteknuckles." Since Fourdrinier forming belts generally have an overalllength of up to about I40 feet, not only are they quite expensive tomanufacture, but considerable expense and downtime is involved inreplacing an excessively worn or fractured Fourdrinier forming belt witha new one.

It is therefore an object of this invention to provide an improved wovenfabric for use as a Fourdrinier forming belt and which comprises a topor face ply of relatively small strands or yarns woven in the desiredfine mesh having at least about 9 percent open area and which fabricalso comprises a bottom or backing ply which also has at least about 9percent open area and whose warp yarns, at least, are of much greatersize than the yarns in the top ply, with the aggregate crosssectionalarea of the warp yarns in the bottom ply also LII being much greaterthan that of the warp yarns in the top ply, thus providing a greatervolume of strand material which must be worn away before the fabric willrupture, and thereby greatly extending the useful life of a Fourdrinierforming belt formed therefrom.

It is a more specific object of this invention to provide a multi-plywoven fabric of the type last described wherein not only the warp yarnsin the bottom ply of the fabric are of much greater size than the yarnsin the top ply, but the weft yarns also are larger in the bottom plythan in the top ply, and the top ply also has a greater number of warpyarns and weft yarns therein than there are in the bottom ply per squareinch of the fabric, at least in the major or formation" area thereof;i.e., the area of the fabric upon which the slurry is deposited.

Some of the objects and advantages of the invention having been stated,others will appear as the description proceeds when taken in connectionwith the accompanying drawings, in which FIG. 1 is a somewhat schematicand partially exploded longitudinal or warpwise sectional view throughone embodiment of the improved multi-ply woven fab ric;

FIG. 2 is a fragmentary transverse or weftwise sectional view takensubstantially along line 2-2 in FIG.

FIG. 3 is a view similar to FIGv 1 showing a second embodiment of themulti-ply woven fabric including reinforcing stuffer warp yarnsextending longitudinally between top and bottom plies of the fabric;

FIG. 4 is a fragmentary transverse or weftwise sectional view takensubstantially along line 4-4 in FIG. 3;

FIG. 5 is a view similar to FIG. 1 showing a third embodiment of themulti-ply woven fabric wherein an intermediate woven ply is positionedbetween the top and bottom plies thereof; and

FIG. 6 is a schematic transverse or weftwise sectional view takensubstantially along line 6-6 in FIG. 5.

Several embodiments of the improved multi-ply Fourdrinier forming beltfabric of this invention are illustrated in the accompanying drawings,all of such fabrics preferably being woven in endless form. Generally,all of the embodiments of the fabric are characterized by havinginterconnected plies or layers of a mesh weave with the size and numberof strands or yarns per square inch in each ply being such that at leastabout 9 percent of the fabric is open and so that water and/or otherliquid will readily flow through the fabric as such water and/or otherliquid is draining from a slurry being deposited on the fabric. Also,the bottom ply of each embodiment of the fabric is woven of relativelylarge strands or yarns as compared to the overlying or top ply toenhance the useful life of the Fourdrinier forming belt formedtherefrom, as will be later described.

Referring more specifically to the drawings, and especially to FIGS. Iand 2, there will be observed the first embodiment of the improvedmulti-ply fabric especially constructed for use as a Fourdrinier formingbelt. As shown, the fabric is broadly designated at 10 and comprises atop, outer or face ply or layer 1] and a bottom, or inner or backing plyor layer 12. The top ply II is prefeably of a plain, relatively finemesh weave having an open area of about 9 percent and includesrelatively small warp yarns l3 interwoven with relatively small weftyarns 14. Bottom ply 12 is of substantially heavier construction thantop ply 11 and is woven of relatively large warp yarns l5 and relativelylarge weft yarns 16. As indicated above the fabric is of meshconstruction so that water or other liquid in a slurry will readilydrain perpendicularly through the fabric.

The top ply 11 has a substantially greater number of warp yarns 13therein than there are warp yarns in the bottom ply 12 per square inchof the fabric 10. Also, top ply 11 has a greater number of weft yarns 14therein than there are weft yarns 16 in bottom ply 12 per square inch ofthe fabric 10, at least in the major or formation" area thereof. Asshown in FIGS. 1 and 2, and as is preferred, top ply 11 has about twiceas many warp yarns 13 therein as there are warp yarns 15 in bottom plyl2, and top ply 11 also has about twice as many weft yarns 14 therein asthere are weft yarns 16 in bottom ply 12.

As heretofore indicated, the warp yarns 1S and weft yarns 16 in thebottom ply 12 of fabric 10 are relatively large as compared to the warpyarns 13 and weft yarns 14 of the top ply 11, and it is preferred thatthe crosssectional area of the individual warp yarns 15 and theindividual weft yarns 16 in the bottom ply 12 is about four timesgreater than the cross-sectional area of each of the warp yarns l3 andweft yarns 14 in top ply 11. Thus, the aggregate cross-sectional area ofat least the warp yarns 15 in bottom ply 12 is substantially greaterthan, and preferably, at least about twice that of, the aggregatecross-sectional area of the warp yarns 13 on top ply 11 of fabric 10.

As indicated above, top ply 11 preferably is woven from relatively smallyarns and is of a relatively fine mesh weave in order to properlyreceive a slurry of water and pulp thereon and to produce a papermaterial of the desired quality. On the other hand, by providing therelatively heavy yarns and substantially lesser number of yarns in thebottom ply 12 of fabric 10, not only do the relatively heavy yarnsprovide a mesh weave having substantially greater or thicker wearingsurfaces thereon than the necessarily relatively small yarns in top ply11 to thereby increase the useful life of the fabric 10, but the heavywarp yarns 15 also have more elongate or blunt warp knuckles on thoseportions thereof which pass beneath and in engagement with the weftyarns 16 in the bottom ply 12 of fabric 10, thus tending to reduce theabrasive action between the lower surface of the backing or bottom ply12 and any rolls or other supporting surfaces over which a Fourdrinierforming belt made from fabric 10 must pass in the formation of paperthereon. Thus, the useful life of a Fourdrinier forming belt made fromthe fabric 10 of FIGS. 1 and 2 would be much greater than that ofconventional single-ply Fourdrinier forming belts having a relativelyfine mesh weave with both the upper and lower faces being formed fromsubstantially the same size, relatively small yarns.

It is important to note that the top and bottom plies ll, 12 of fabric10 are practically independent of each other with the exception of aplurality of relatively fine interlacing binder warp yarns 17 whichextend warpwise of fabric 10 but are spaced weftwise apart from eachother, Thus, in a Fourdrinier forming belt made from fabric 10, the topand bottom plies 11, 12 may shift or yield relative to each other assuccessive portions of such belt are moving in engagement with thecylindrical surfaces of supporting rolls of a papermaking machine,thereby reducing the abrasive action of bottom ply 12 against suchsurfaces.

It is preferred that there are about one-eighth to onehalf as manybinder warp yarns 17 in fabric 10 as there are warp yarns 13 is top ply11 thereof. Also, the binder warp yarns 17 may be somewhat smaller thanthe top ply yarns 13, 14 so that the binder warp yarns will not formundesirable gaps between the adjacent top ply warp yarns l3 straddlingthe binder warp yarns 17. As preferred, the binder warp yarns 17 arelooped beneath all of the weft yarns 16 in bottom ply 12 of fabric 10,but the binder warp yarns 17 are looped over only the alternate weftyarns 14 in top ply 1] of fabric 10. The plain mesh weave constructionof each ply 11, I2 is shown by way of example only, it being understoodthat the fabric may be embodied in other suitable weave constructions,such as a twill or semi-twill weave. for example. In any event, the finemesh top ply l1, and thus the bottom ply 12, must have an open areathroughout the same of at least about 9 percent with the openings orinterstices through each ply being substantially uniformly distributedthroughout the same.

Although only a relatively small portion of fabric 10 is shown in FIGS.1 and 2, it is well known that Fourdrinier forming belt fabrics aregenerally woven in endless form with the weft yarns 14, 16 in the twoplies ll, 12 being continuous and extending in a helical manner from oneedge of the belt formed therefrom to the other and throughout the upperand lower reaches of the Fourdrinier forming belt made from such fabric.Of course. the warp yarns extend transversely across such a Fourdrinierforming belt. Accordingly, since the relatively large weft yarns 16might otherwise cross over or outside of the smaller weft yarns 14 atwhat normally would be the selvage of the fabric during weaving, theendless fabric may be woven with the relatively small weft yarns 14located inside of the tubular fabric and with the larger weft yarns 16,which are lesser in number than the small weft yarns 14, being locatedoutside of the fabric. Of course, after cutting each warpwise lengthfrom the fabric, as woven, to form a Fourdriniere forming belt of thedesired width, the cut length of fabric would be obverted prior to beinginstalled on a Fourdrinier papermaking machine so as to present thefiner mesh surface of the fabric on the outside of the belt forreceiving the slurry thereon.

It is important to note that, by weaving the fabric 10 in endless formto form an endless belt thereof, as indicated above, the weft yarns 14,16 are substantially straight throughout the length of the respectiveendless plies ll, 12, thereby greatly enhancing the lengthwise stabilityof the fabric. Such stability may be further improved by heat-settingthe fabric 10 if it is formed of synthetic yarns, as preferred. Ofcourse, the warp yarns 13, 15 of the respective plies 11, 12 extendwidthwise of such endless fabric and thus curve over and under therespective substantially straight weft yarns 14, 16 as shown in FIG. 1.Thus, the warp yarns 13, 15 are formed with knuckles which constitutewearing surfaces on the outer or distal surfaces of the plies l1, 12.

In order to provide a fabric which, when formed into a Fourdrinierforming belt, will have further enhanced stability in the widthwisedirection of the belt; i.e., in the warpwise direction of the fabric, asecond embodiment 10a of the fabric is shown in FIGS. 3 and 4 providedwith stuffer warp yarns 20 throughout the length of the woven fabric.The second embodiment of the fabric includes top and bottom layers orplies I1, 12 which may be identical to the plies ll, 12 of fabric I0.Thus, all other components of fabric a will bear the same referencecharacters as are applied to like components shown in FIGS. 1 and 2 toavoid repetitive description. It will be noted that the stuffer warpyarns 20 extend warpwise and in a relatively straight condition in FIGS.3 and 4. The stuffer warp yarns 20 may be made from any suitable pliablematerial which may be of the same or of a different type of materialfrom that of the various yarns l3, l4, l5, 16, 17.

The stuffer warp yarns 20 preferably are somewhat larger than warp andweft yarns l3, 14 in top ply 13 of fabric 10a. Any desired number ofstuffer warp yarns may be provided. As shown in FIG. 4, there are abouttwice as many warp yarns 13 in top ply 11 as there are stuffer warpyarns 20 between the plies, for example. It is apparent that, byproviding stuffer warp yarns 20 in fabric 100, enhanced warpwisestability is obtained and, consequently, a Fourdrinier forming belt madefrom fabric 10a would have enhanced widthwise stability.

In FIGS. 5 and 6 a third embodiment of the fabric is shown which isbroadly designated at 10b and includes three layers or plies, namely,atop ply 11, an intermediate ply 12 and a bottom ply 22. The top andintermediate plies 11, 12 of the fabric 10b may be identical to the topand bottom plies 11, 12, respectively, of the fabric 10 shown in FIGS. 1and 2. Accordingly the various components of the top and intermediateplies 11, 12 of fabric 10!) will bear the same reference characters asare applied to like components of plies ll, 12 shown in FIGS. 1 and 2,where applicable, to avoid repetitive description. The top andintermediate plies 11, 12 of fabric 10b are interconnected by binderwarp yarns 17 in essentially the same manner as that in which binderwarp yarns l7 interconnect the top and bottom plies ll, 12 of the fabric10 in FIGS. 1 and 2.

The bottom ply 22 of the fabric 10b shown in FIGS. 5 and 6 includes warpyarns 25 interwoven with weft yarns 26, but the warp yarns 25 and weftyarns 26 in bottom ply 22 of fabric 10b are substantially larger thanthe respective warp yarns and weft yarns 16 in the intermediate ply 12of fabric 10b. Additionally, intermediate ply ]2 of fabric 10b has asubstantially greater number of warp yarns and weft yarns therein thanthat present in bottom ply 22.

By way of example, there are shown in FIG. 5 twice as many warp yarnsand weft yarns 15, 16 in the intermediate ply 12 of fabric 10b as thereare respective warp yarns 25 and weft yarns 26 in the bottom ply 22. Itis preferred that the warp yarns 25 and weft yarns 26 of bottom ply 22of fabric 10b are approximately four times the size of the respectivewarp yarns l5 and weft yarns l6 ofthe intermediate ply 12 in fabric 10b.In any event, each of the three plies 11, I2, 22 of fabric 10b (FIGS. 5and 6) is in the form of a mesh weave having at least about 9 percent ofits surface area open for the drainage of liquid therethrough when inuse.

A plurality of binder warp yarns 27, preferably of about the same sizeas binder warp yarns 17, are provided for interconnecting theintermediate and bottom plies 12, 22 of fabric 10h. In this instance,binder warp yarns 27 are shown extending beneath all of the weft yarns26 of bottom ply 22, but they only extend over alternate weft yarns 16in the intermediate ply 12 of fabric 10!). If desired, binder warp yarns17 might be omitted in fabric 10b. However, the upper bights of binderwarp yarns 27 then would be looped over spaced top ply weft yarns 14 offabric 10b to bind all three plies 11, I2, 22 together. In otherrespects, the third embodiment 10b of the fabric may be of substantiallythe same construction as the first and second embodiments of the fabricindicated at 10 and 100. Therefore. a further description of the fabric10!) is deemed unnecessary.

While it is preferred that each of the three embodi ments of the fabricdisclosed herein is woven from synthetic yarns, it is to be understoodthat the yarns may be in the form of metal strands, thay may be in theform of metal strands coated with a plastic material, they may be in theform of continuous multifilaments or monofllaments, they may be formedfrom yarns of natural or man-made staple fibers or they may be of anysuitable combination of filaments and/0r fibers of different types. Inthe event that metal or plastic-coated metal yarns are present in any ofthe fabrics 10, 10a. 10b, it is preferred that the top ply ll of eachsuch fabric is woven of synthetic continuous-filament or staplefiberyarns, since synthetic yarns are generally less brittle than metalyarns, and synthetic yarns generally provide a more durable and smoothersurface for receiving a slurry of pulp and water thereon than is thecase with metal yarns.

As heretofore indicated, the yarns 13, 14 in the top ply 11 of eachfabric 10, 10a, 10b are relatively small size yarns and preferably donot exceed several hundred denier in size. Thus, for example, if theyarns 13, 14 are synthetic yarns, each of them may be of about 100 to400 denier nylon, acrylic, polypropylene or other synthetic strandmaterial. Also, if synthetic yarns are used, it is preferred that theyare continuousfilament yarns since they would normally be of greatertensile strength than staple fiber synthetic yarns. Of course, the yarnsl5, 16 in the bottom ply 12 of fabrics 10, 10a and in the intermediateply 12 of fabric 10b should be at least about four times the size of theyarns l3, 14. Further, if the yarns 15, 16 are synthetic; e.g., nylon,acrylic, polypropylene or other synthetic strand material, each of themmay be in the range of about 400 to L600 denier. The yarns 25, 26 inbottom ply 22 of fabric 10b (FIGS. 5 and 6) may be about four times thesize of the yarns 15, 16 in ply 12 of fabric 10b.

It is apparent that wire strands and/or staple-fiber yarns used in placeof any of the synthetic yarns 13-15, 25, 26 may be of sizes comparablewith the synthetic yarn sizes mentioned above.

Non-limiting examples illustrative of many different fabrics which maybe constructed in accordance with this invention will now be given. Atwo-ply fabric woven in accordance with the fabric 10 of FIGS. 1 and 2has a top ply 1] whose warp yarns 13 are each approximately 210 denierpolyester plied yarns, with three plies of denier multifilamentpolyester strands forming each warp yarn 13. About of such wary yarnsper inch are interwoven with about 48 polyester weft yarns per inch,each weft yarn 14 being approximately 300 denier and formed of threeplies of I00 denier multifilament polyester strands. A bottom ply 12 ofthe illustrative fabric 10 of FIGS. 1 and 2 is formed of about 40 warpyarns per inch interwoven with about 24 weft yarns per inch. Each of thewarp yarns 15 in the bottom ply 12 of the fabric 10 is formed of threeplies of 300 denier multifilament polyester strands so that each warpyarn 15 has a total denier of 900. The weft yarns 16 in the bottom ply12 of the illustrative fabric are each formed of three plies of 440denier multifl ament strands so that each weft yarn 16 has a total denier of approximately L320. The binder warp yarns 17 are approximatelyl02 denier multifilament polyester yarns and are alternately arrangedwith respect to the warp yarns in the bottom ply 12. Thus, 40 binderwarp yarns are provided per inch of the fabric 10.

As heretofore indicated, in weaving a typical fabric 10a according tothe second embodiment of FIGS. 3 and 4, the stuffer warp yarns 20preferably are somewhat larger than the warp and weft yarns l3, 14 inthe top layer 10 and there are about twice as many warp yarns 13 in thetop ply as there are stuffer warp yarns 20 between the plies. Thus, afurther illustrative example of the fabric 100 of FIGS. 3 and 4 isdeemed unnec essary.

In a typical fabric woven in accordance with the fabric 10b of FIGS. 5and 6, the top and intermediate plies l1, 12 of the fabric 10b may beconstructed in the manner as described above in the example of thefabric 10, and the bottom ply 22 of fabric 10b may be formed ofapproximately 20 ends per inch of warp yarns 25 with each warp yarn 25being approximately 3600 denier and being formed of three plies of 1200denier multifilament polyester strands. In such an instance, 12 ends ofweft yarns 26 would be provided per inch in the bottom ply 22 of fabric10b, with each end of weft yarn 26 being approximately 4800 denier andpreferably being formed of three plies of 1600 denier polyester strands.It is apparent that many different sizes and types of yarns may be usedin forming the various embodiments of the fabric in accordance with thisinvention. Thus, a description of additional examples of the fabric isdeemed unnecessary.

It is thus seen that l have provided a multi-ply woven fabric which isparticularly useful in the construction of an endless Fourdrinierforming belt and is especially constructed to withstand flexing, hightension and abrasion incidental to paper manufacutre. It is seen furtherthat the fabric comprises at least two interconnected plies, each ofwhich is formed of respective interwoven warp and weft yarns with theinterconnected plies including at least a top ply and a bottom plytherein. The top ply includes relatively small size warp yarns and weftyarns, and the bottom ply includes relatively large warp yarns and weftyarns as compared to the size of the warp yarns in the top ply. The topply also has a substantially greater number of warp yarns and weft yarnstherein than there are present in the bottom ply in each instance. Also,the aggregate crosssectional area of the warp yarns in the bottom ply,in each instance, is substantially greater than the aggregatecrosssectional area of the warp yarns in the top ply of the fabric withthe result that a substantially greater amount of yarn is present on thebottom of the fabric to be subjected to the wear and abrasion of thesupporting rolls and other supporting surfaces over which a Fourdrinierforming belt must pass and thereby greatly extending the useful life ofa Fourdrinier forming belt made from the fabric of the present inventionas com pared to those used heretofore.

It is preferred that each of the embodiments of the fabric 10, 10a, 10bis woven in endless form, as described herein, so that the weft yarnsthereof will extend lengthwise around the Fourdrinier belt formedtherefrom. It is apparent, however, that each embodiment of the fabricmay be woven of the desired weftwise width and in indefinite warpwiselengths, after which the fabric may be cut to the desired warpwiselengths and opposite ends thereof then may be suitably spliced togetherto form an endless Fourdrinier belt therefrom.

In the drawings and specification, there has been set forth, preferredembodiments of the invention, and although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation.

That which is claimes is:

l. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each having an open area of atleast about 9 percent and each ply being formed of respective interwovenwarp and weft yarns, binder warp yarns interwoven with andinterconnecting said plies, said plies including a top ply and a bottomply, and said top ply being formed of a considerably greater number ofwarp yarns and weft yarns per square inch than said bottom ply with atleast the warp yarns in said top ply being substantially smaller thanthe warp yarns in said bottom ply, and the aggregate crosssectional areaof the yarns in said bottom ply being substantially greater than that ofthe yarns in said top ply per square inch of the fabric.

2. A multi-ply woven fabric according to claim 1, wherein said top plyincludes about twice as many warp yarns therein as there are in saidbottom ply.

3. A multi-ply woven fabric according to claim 1, wherein each of saidbinder warp yarns is interwoven back and forth between the two pliesinterconnected thereby and extends over spaced weft yarns only of saidtop ply, but extends under all of the weft yarns in said bottom ply.

4. A multi-ply woven fabric according to claim I, wherein said binderwarp yarns are smaller than said warp yarns in said top ply.

5. A multi-ply woven fabric according to claim 1, wherein the warp yarnsin each of said plies extend over and under all of the weft yarns in therespective ply, and wherein only said binder warp yarns extend betweenand interconnect the adjacent plies.

6. A multi-ply woven fabric according to claim 1, including a pluralityof stuffer warp yarns positioned between said top and bottom plies ofthe fabric.

7. A multi-ply woven fabric according to claim 1, including anadditional intermediate ply of interwoven warp and weft yarns positionedbetween said top and bottom plies, and interconnect binder warp yarnsconnecting said intermediate ply to said top and bottom plies.

8. A multi-ply woven fabric according to claim 7, wherein said binderwarp yarns include upper binder warp yarns extending between andinterwoven with and interconnecting said top ply and said intermediateply, and lower binder warp yarns extending between and interwoven withand interconnecting said intermediate ply and said bottom ply.

9. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each having an open area of atleast about 9 percent and each ply being formed of respective interwovenwarp and weft yarns, binder warp yarns interwoven with andinterconnecting said plies. said plies including a top ply and a bottomply, said top ply being formed of a considerably greater number of warpyarns and weft yarns than said bottom ply, and the size of the warp andweft yarns in the bottom ply being substantially larger than the warpand weft yarns in the top ply,

10. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each formed of respectiveinterwoven warp and weft yarns, the size and number of warp and weftyarns per square inch of each respective ply being such that at leastabout 9% of each ply is open area, binder warp yarns interwoven with andinterconnecting said plies, said plies including a top ply and a bottomply, said top ply being formed of relatively small warp yarns andrelatively small weft yarns, said bottom ply including relatively largewarp yarns compared to the warp yarns in said top ply, said top plyhaving about twice as many weft yarns therein as there are in saidbottom ply per square inch of the fabric, said top ply also having agreater number of warp yarns therein than there are in said bottom ply,and the aggregate cross-sectional area of the warp yarns in said bottomply being substantially greater than the aggregate cross-sectional areaof the warp yarns in said top ply.

11. A multiply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising a top ply, a bottom ply, and an intermediate plybetween said top and bottom plies, binder warp yarns interwoven with andinterconnecting all of said plies, each of said plies comprisinginterwoven warp and weft yarns with the size and number of warp and weftyarns per square inch of each ply being such that at least about 9percent of each ply is open area, said top ply having about twice asmany weft yarns therein as there are in said intermediate ply, saidintermediate ply having about twice as many weft yarns therein as thereare in said bottom ply, and the warp yarns and weft yarns of saidintermediate and bottom plies being relatively large as compared to thewarp yarns and weft yarns in said top ply.

12. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainageof liquid therethrough from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each formed of respectiveinterwoven warp yarns and weft yarns with the size and number of warpand weft yarns per square inch of each ply being such that at leastabout 9 percent of each ply is open area, binder warp yarns interwovenwith and interconnecting said plies. said plies including a top ply anda bottom ply, said top ply having a substantially greater number of warpyarns and weft yarns per square inch of said fabric than the bottom ply,said yarns in said top ply being substantially smaller than the yarns insaid bottom ply, said binder warp yarns being relatively small andlooped over weft yarns in said top ply and beneath weft yarns in saidbottom ply, and a plurality of stuffer warp yarns positioned betweensaid top and bottom plies of said fabric.

13. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each having an open area of atleast about 9% and each ply being formed of respective interwoven warpand weft yarns, binder yarns interwoven with and interconnecting saidplies, said plies including a top ply and a bottom ply, and said top plybeing formed of a considerably greater number of warp yarns and weftyarns per square inch than said bottom ply with at least the warp yarnsin said top ply being substantially smaller than the warp yarns in saidbottom ply, and the aggregate crosssectional area of the yarns in saidbottom ply being substantially greater than that of the yarns in saidtop ply per square inch of the fabric.

1. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each having an open area of atleast about 9 percent and each ply being formed of respective interwovenwarp and weft yarns, binder warp yarns interwoven with andinterconnecting said plies, said plies including a top ply and a bottomply, and said top ply being formed of a considerably greater number ofwarp yarns and weft yarns per square inch than said bottom ply with atleast the warp yarns in said top ply being substantially smaller thanthe warp yarns in said bOttom ply, and the aggregate cross-sectionalarea of the yarns in said bottom ply being substantially greater thanthat of the yarns in said top ply per square inch of the fabric.
 2. Amulti-ply woven fabric according to claim 1, wherein said top plyincludes about twice as many warp yarns therein as there are in saidbottom ply.
 3. A multi-ply woven fabric according to claim 1, whereineach of said binder warp yarns is interwoven back and forth between thetwo plies interconnected thereby and extends over spaced weft yarns onlyof said top ply, but extends under all of the weft yarns in said bottomply.
 4. A multi-ply woven fabric according to claim 1, wherein saidbinder warp yarns are smaller than said warp yarns in said top ply.
 5. Amulti-ply woven fabric according to claim 1, wherein the warp yarns ineach of said plies extend over and under all of the weft yarns in therespective ply, and wherein only said binder warp yarns extend betweenand interconnect the adjacent plies.
 6. A multi-ply woven fabricaccording to claim 1, including a plurality of stuffer warp yarnspositioned between said top and bottom plies of the fabric.
 7. Amulti-ply woven fabric according to claim 1, including an additionalintermediate ply of interwoven warp and weft yarns positioned betweensaid top and bottom plies, and interconnect binder warp yarns connectingsaid intermediate ply to said top and bottom plies.
 8. A multi-ply wovenfabric according to claim 7, wherein said binder warp yarns includeupper binder warp yarns extending between and interwoven with andinterconnecting said top ply and said intermediate ply, and lower binderwarp yarns extending between and interwoven with and interconnectingsaid intermediate ply and said bottom ply.
 9. A multi-ply woven fabricof mesh construction for use as a Fourdrinier forming belt andespecially constructed to permit drainage therethrough of liquid from aslurry received thereon and to withstand flexing, high tension andabrasion incident to paper manufacture, said fabric comprising at leasttwo plies each having an open area of at least about 9 percent and eachply being formed of respective interwoven warp and weft yarns, binderwarp yarns interwoven with and interconnecting said plies, said pliesincluding a top ply and a bottom ply, said top ply being formed of aconsiderably greater number of warp yarns and weft yarns than saidbottom ply, and the size of the warp and weft yarns in the bottom plybeing substantially larger than the warp and weft yarns in the top ply.10. A multi-ply woven fabric of mesh construction for use as aFourdrinier forming belt and especially constructed to permit drainagetherethrough of liquid from a slurry received thereon and to withstandflexing, high tension and abrasion incident to paper manufacture, saidfabric comprising at least two plies each formed of respectiveinterwoven warp and weft yarns, the size and number of warp and weftyarns per square inch of each respective ply being such that at leastabout 9% of each ply is open area, binder warp yarns interwoven with andinterconnecting said plies, said plies including a top ply and a bottomply, said top ply being formed of relatively small warp yarns andrelatively small weft yarns, said bottom ply including relatively largewarp yarns compared to the warp yarns in said top ply, said top plyhaving about twice as many weft yarns therein as there are in saidbottom ply per square inch of the fabric, said top ply also having agreater number of warp yarns therein than there are in said bottom ply,and the aggregate cross-sectional area of the warp yarns in said bottomply being substantially greater than the aggregate cross-sectional areaof the warp yarns in said top ply.
 11. A multi-ply woven fabric of meshconstruction for use as a Fourdrinier forming belt and especiallyconstructed to permit drainage therethrough of liquid from a slurryreceived thereon and to withstand flexing, high tension and abrasionincident to paper manufacture, said fabric comprising a top ply, abottom ply, and an intermediate ply between said top and bottom plies,binder warp yarns interwoven with and interconnecting all of said plies,each of said plies comprising interwoven warp and weft yarns with thesize and number of warp and weft yarns per square inch of each ply beingsuch that at least about 9 percent of each ply is open area, said topply having about twice as many weft yarns therein as there are in saidintermediate ply, said intermediate ply having about twice as many weftyarns therein as there are in said bottom ply, and the warp yarns andweft yarns of said intermediate and bottom plies being relatively largeas compared to the warp yarns and weft yarns in said top ply.
 12. Amulti-ply woven fabric of mesh construction for use as a Fourdrinierforming belt and especially constructed to permit drainage of liquidtherethrough from a slurry received thereon and to withstand flexing,high tension and abrasion incident to paper manufacture, said fabriccomprising at least two plies each formed of respective interwoven warpyarns and weft yarns with the size and number of warp and weft yarns persquare inch of each ply being such that at least about 9 percent of eachply is open area, binder warp yarns interwoven with and interconnectingsaid plies, said plies including a top ply and a bottom ply, said topply having a substantially greater number of warp yarns and weft yarnsper square inch of said fabric than the bottom ply, said yarns in saidtop ply being substantially smaller than the yarns in said bottom ply,said binder warp yarns being relatively small and looped over weft yarnsin said top ply and beneath weft yarns in said bottom ply, and aplurality of stuffer warp yarns positioned between said top and bottomplies of said fabric.
 13. A multi-ply woven fabric of mesh constructionfor use as a Fourdrinier forming belt and especially constructed topermit drainage therethrough of liquid from a slurry received thereonand to withstand flexing, high tension and abrasion incident to papermanufacture, said fabric comprising at least two plies each having anopen area of at least about 9% and each ply being formed of respectiveinterwoven warp and weft yarns, binder yarns interwoven with andinterconnecting said plies, said plies including a top ply and a bottomply, and said top ply being formed of a considerably greater number ofwarp yarns and weft yarns per square inch than said bottom ply with atleast the warp yarns in said top ply being substantially smaller thanthe warp yarns in said bottom ply, and the aggregate cross-sectionalarea of the yarns in said bottom ply being substantially greater thanthat of the yarns in said top ply per square inch of the fabric.